What 98 octane actually does for your timing

Setting the baseline on the dyno

The car arrived with 14,832 miles on the clock and a warm engine. We kept the workshop at a steady 19.4°C to ensure the air density stayed consistent throughout the afternoon. Our first task was to drain the existing fuel system to remove any variables. We started with standard 95 octane pump fuel from the local station. For an Italian V12 with a high compression ratio, this is the bare minimum the manufacturer allows. We performed 4 warm-up pulls to let the long-term fuel trims settle before recording the actual data. It's important to remember that these engines are designed for high-velocity airflow, and the fuel chemistry dictates how early the spark can fire.

During the 95 octane runs, we monitored the ignition timing advance using the factory OBD port and our own sensors. By the time the engine reached 5,400 RPM, the knock sensors were already active. The ECU began pulling timing to prevent pre-detonation. Honestly, the engine sounded fine to the naked ear, but the software was working hard to protect the pistons. We recorded a peak of 674.2 horsepower, which is about 11.7 horsepower lower than the factory claims for this specific chassis. Heat cycles matter here because as the intake manifold temp climbed to 42.1°C, the power drop became even more pronounced during the final runs.

The engine sounded fine to the naked ear, but the software was working hard to protect the pistons.

Switching to 98 octane and the immediate response

After the 95 octane tests, we flushed the lines and filled the tank with premium 98 octane. We didn't change any settings on the car. We simply let the ECU 'discover' the higher knock resistance of the new fuel. On the first pull, the timing advance remained cautious, as the computer still had the 95 octane maps in its short-term memory. However, by the third pull, we saw the ignition curve start to climb. The spark was firing 3.2 degrees earlier in the combustion stroke compared to the previous fuel. This shift allows the pressure inside the cylinder to build more effectively, pushing the piston down with more force right at the optimal moment.

The results were clear on the graph. The 98 octane allowed the engine to hit 689.8 horsepower. That is a gain of 15.6 horsepower just by changing the liquid in the tank. More importantly, the torque curve smoothed out between 3,200 and 6,800 RPM. On the 95 octane, the curve had several small dips where the ECU was stuttering the timing to manage knock. With the 98 octane, those dips disappeared. The car felt more linear and responsive on the dyno rollers. This isn't just about the peak number; it is about how the car delivers that power throughout the entire rev range during hard acceleration.

We saw a gain of 15.6 horsepower just by changing the liquid in the tank.

Back pressure check and exhaust temperatures

While the power gains are interesting, we also looked at the thermal data. Using cheaper fuel actually makes the engine run hotter. With the 95 octane, our sensors recorded exhaust gas temperatures (EGTs) that were about 28°C higher than the 98 octane runs. When the timing is retarded, the combustion process continues as the exhaust valve opens, sending more heat into the manifold. Over a long drive or a track session at Goodwood, this extra heat puts unnecessary stress on the valve seats and the exhaust gaskets. If you are running our Titanium grade 2 system, the metal handles the heat well, but the internal engine components prefer the cooler burn of higher octane.

We also performed a back pressure check on the system. High-octane fuel results in a more complete burn within the cylinder, which means the exhaust gases are slightly more predictable in their expansion. This helps with scavenging, especially in the high RPM range where the V12 really breathes. To be upfront, you probably won't feel 15 horsepower while driving through Southampton traffic. But you will feel the difference in throttle crispness when you're merging onto the A27. The engine feels 'sharper' because the ECU isn't constantly fighting against the fuel's tendency to explode too early.

The economic reality for car owners

Let's look at the costs. Filling a 92-litre tank with 98 octane costs about £14.20 more than filling it with 95. If you drive 5,000 miles a year, you are looking at an extra cost of roughly £187 over twelve months. Compare that to the cost of a single fuel injector service or the price of replacing a heat-damaged sensor. In our workshop, we often see cars with carbon buildup on the piston crowns at the 12,000-mile service mark. Much of this comes from poor combustion cycles caused by low-grade fuel. Using the better fuel is essentially a preventative maintenance step that also happens to give you more power.

By the way, we noticed that the ECU learning cycle for this Ferrari took about 9 miles of varied driving to fully adapt to the better fuel. You can't just put a splash of 98 in and expect an immediate 15-horsepower jump. The system needs to see consistent data from the knock sensors across different load points before it trusts the fuel enough to advance the timing. (Heads-up: don't mix fuel grades in the same tank if you want clean data; wait until you are nearly empty before switching). For any Italian performance car, the 98 octane is the only way to ensure you are actually getting the performance you paid for when you bought the vehicle.

Using the better fuel is essentially a preventative maintenance step.